The present invention relates to a bumper system for a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Bumpers are typically installed across the front and rear of motor vehicles to absorb impact energy in the event of a collision to substantially prevent damage to the support structure of the vehicle. The bumper system normally includes a shock-absorbing component, like a crash box, to convert the impact energy into deformation work, and a crossbeam to introduce the energy as a result of the impact into the crash box. The bumper system is constructed to install the end face of the crash box in midsection on the side rail of the motor vehicle and to introduce the impact energy with smallest possible bending moment via the crossbeam into the crash box and thus also into the side rail.
Crossbeams constructed in the form of a two-chamber hollow section are known and welded or threadably engaged onto crash boxes. In crash tests, the stiffness of the crossbeam is an important factor with respect to the behavior of the crash boxes. Bumpers are inspected by various crash tests involving high-speed tests and low-speed tests. Crash tests at higher speeds demand a high stiffness of the crossbeams in particular in the middle part thereof, whereas crash tests at lower speed demand a higher ductility of the bumper which is realized by crash boxes. Reconciliation of these seemingly contradictory requirements poses a problem heretofore to optimize bumper designs when considering the acceleration encountered in the event of a crash in relation to the deformation path.
It would therefore be desirable and advantageous to provide an improved bumper system which obviates prior art shortcomings and which exhibits a crash behavior which meets safety standards demanded by high-speed and low-speed crash tests.